The invention relates to a method for estimating at least one component placement position on a substrate at which a component is to be placed; the component placement position is estimated on the basis of a position of at least one mark on the substrate. The invention also relates to a device suitable for carrying out such a method.
According to a conventional method, which is described in EP-A1-0 042 977, the position of a number of marks on a substrate are measured and are compared to the marks' expected positions. Based on differences between the marks' measured and expected, a transformation is applied to the expected or theoretical component placement positions on the substrate at which components are to be placed. As a result, corrections may be made for errors that may occur as a result of, for example, misalignment of a substrate in a component placement device, stretch of the substrate, etc.
In the last few decades, the components to be placed have become increasingly smaller. Moreover, these smaller components must be positioned on the substrate with ever increasing precision. If the component placement position is determined relatively inaccurately, the result will be an incorrect placement of the component at the component placement position and, in turn, the substrate will be rejected during a subsequent process.
What is needed, therefore, is an apparatus and a methodology that address at least one if not more of the deficiencies that afflict conventional practice, as previously described.